Shaft-sealing device



E. T. WILLIAMS.

SHAFT SEALING DEVICE.

APPucATloN FILED JAN.14.1919.

1,327,002. Patented J an. (5, 1920.

WW LU! ,www l JNVENTOR EDWARD T. WILLIAMS, OF NEW YORK, N. Y.

SHAFT-SEALING DEVICE.

Specication of Letters Patent.

Patented Jan. c, 1920.

Application filed January 14, 1919. Serial No. 271,043.

vices, of which the following is a full, clear,v

and exact description.

In machines for handling gases, as for ex- Iample pumps, compressors, blowers, eX-

hausters, and the like, in which a driving `or other rotating shaft extends into the ma- 4 chine, considerable difficulty has been experienced in preventing leakage out of or into the machine along the shaft. In refrigerating apparatus, in which ammonia, ethyl chlorid, or other offensive gas is used, lthe problem is especially important. It is accordingly the chief object of my present invention Ito provide an improved seal for the shaft, which will be positively gas-tight under running conditions. A further object is to 4provide a device of the character indicated, in which the sealing eifect will be favored rather than impaired-by any wear to which the relatively movable parts are sub jected in use. To these and other ends the invention resides in the novel features of construction, arrangements of parts, and combinations of elements, hereinafter described.

Of the various embodiments of which the invention is capable I have selected for illustration and specific description herein the one which at the resent time is believed to exhibit the invention in its most convenient and eective form. This embodiment is illustrated in the accompanying drawing, in which- Figure 1 is a-longitudinal section.

Fig. 2 is a detail view also in longitudinal section, of a modification- Referring to the drawing, 10 indicates the casing of a compressor or other machine having a rotary shaft 11 extending into the same from the outside, for example through a neck 12. The neck is threaded to receive a. threaded cap 13 -encircling the shaft. 13e-- tween the neck and the cap a gasket or washer, not shown, may be provided. It will be understood that the cap and neck are stationary relatively to each other and to the shaft, except. of course, that the cap may7 be rotated on the neck for removal or adJustment.

Encircling the shaft., next. to the cap 13, is

a flexible sealing element 14, hermetically attached to the cap. This element is preferably a bellows, of thin sheet metal, capable of longitudinal expansion and contraction. At its other end the sealing element or bel'- lows 4is connected in a gas-tight manner to a collar 15 in which the shaft rotates. On the outer face of the collar is an annular rib 16 cooperating with an annular groovel 17 in the adjacent face of a flange on the sleeve 18 fixed non-rotatably on the shaft, so as to revolve therewitlnby means of a pin 19 extending through the sleeve at a suitable point in the annular groove 19a. The sleeve 18 is threaded to receive a cap 2O which serves to compress a solid packlng, for example., lead, in a groove 21 in the outer face of the flange. This cap is in the form of a solid cup, which covers the pin 19, so that no leakage can occur through the holes formed in sleeve 18 to receive the pin. l

The face of the rib 16 and the bottom of the groove 17 are ground together so that their plane of contact is strictly perpendicular to the axis of the shaft, and inasmuch as these surfaces are in rubbing contact the gas-tight fit thereat is constantly improved rather than impaired when the machine is in operation.

liVhen a. fluid pressure is generated in the casing 10 any gas leaking into the bellows tends to expand the latter-,and hence presses the rib 16 still more firmly into its seat, but

at the same time the bellows permits considerable side-play, such as may be due to the shaft not being truly straight or truly cylindrical, without opening the joint at the rib. Vhen the machine is idle the tension of the bellows (which is ordinarily put under slight compression by adjusting the collar 13) holds the sealing rib in its seat with sufficient pressure to prevent slow leakage; but if not, additional pressure may be obtained by means of a coil spring 22. Preferably the spring is seated in grooves 23 to hold it out of contact with the shaft.

The gas-tight cap 20 is an advantageous feature. It screws u firmly against the packing 21 and thus e ectuallyl prevents the escape of oil as well as gas, and at the same y 18 and the non-rotating collar 15 is slight, but nevertheless may put considerable torsional stress on the rather delicate bellows 14, especially when the rotation of the shaft begins. To obviate this drawback I secure to the collar 13, for example by means of screw threads as shown, an. outer sleeve 25, which incloses the bellows. The other end of the sleeve is provided with axially extending slots 26, which are engaged by screws 27 threaded in the collar 15. The bellows can therefore expand and contract freely, the ,collar 15 moving axially on the shaft, but all torsional stresses on the said collar are taken by the sleeve instead of by the bellows. The latter is thus fully protected from twisting stresses, which might rupture it, and is also protected from in]ury by blows or other accidents.

A simpler construction for the outer end of the shaft, which is particularly useful with shafts of small diameter, is illustrated in Fig. 2. In this -form the collar 18 is omit- V .ted and the rib 16a (corresponding to the rib 16 in Fig. l) is in the form of an axial lflange around the opening in collar 15. This flange bears against the bottom of a rabbet 17- around the openingin the cap 2Oa to provide a gas-tight joint. The shaft 11 is threaded at itsend, and one or more of the threads are turned off. Back of the threads (toward the leftin Fig. 2) the opening in the cap makes a smooth, close t with the shaft.

The friction between the'rotatin cap .20a and the non-resisting collar 15u ten s to hold the cap and thus tends to make it rotate i more slowly than the shaft. This tendency may be utilized to keep the cap tight on the shaft. Thus if the rotation of the shaft is in the direction of the arrow, a left-hand thread is used, with the result that any l'movement of rotation of the shaft relative to the cap will screw the cap farther upon the shaft and thus secure it more firmly thereon. f

It is to be understood that the invention is 4not limited to the specific constructions herein described but can be embodied in other forms without departure from its spirit as defined by the following claims.

I claim:

1. In a shaft-sealin device of the class described, in combination, a casing, a shaft extending out of the casing, a non-rotating axially expansible sealing device surrounding the shaft and connected at its inner end with the casing and having an axially exansible portion, and a cap secured over and inclosing the outer end of the shaft to rotate therewith and coperating with the cuter end of the sealing device to prevent leakage.

2. In a shaft-sealing device of the class described, in combination, a casing, a shaft extending out of the casing, a sealing device surrounding the shaft and associated at its inner end with the casing and having an axially expansible portion; and a coupling member secured on the shaft at the outer end thereof to rotate with the shaft and cooperating with the outer end of the sealing device to prevent leakage.

3. In a shaft-seiig device of the class described, in combination, a casing, a shaft extending out of the casing, a sealing device surrounding the shaft and associated at its inner end with the casing and having an axially expansible portion; and a coupling member to rotate with the shaft, comprising a ca secured over the outer end of the shaft an coperating with the sealing member to prevent leakage'.

4. In a shaft-sealing device of the class .described, in combination, a. shaft, anl axially; expansible member surrounding the shaft, a sleeve mounted on the yshaft at the outer end thereof and coperating with the outer end of the sealing member to prevent leakage thereat, a pin extending through the side of the sleeve into the shaft to prevent rotation of the collar relative to the shaft; and a cap secured over the outer1 end of the shaft to cover said pin and coperating with the sleeve to prevent leakage.

5. Ina shaft sealing device of the class described, in combination, a shaft, an axially expansible sealing member surrounding the shaft, a sleeve mounted on the shaft at the outer end thereof and coperating with the outer end of the sealing member to prevent leakage thereat, means for securing the sleeve on the shaft; and a coupling member comprising a cap secured on the sleeve to rotate the same and the shaft, and covering the outer end of the shaft and cooperating With the sleeve to prevent leakage. 6. In a shaft-sealing device of the class described, in combination, a shaft, a sealing device surrounding the shaft and having an axially expansible portion, and a coupling member comprising an externally ribbed cap connected with and inclosing the outer end of the shaft to rotate the shaft and prevent leakage at its end, and coperating with the sealing device to prevent leakage between the two. l

In testimony whereof I hereunto aiiix my signature. v

EDWARD T. WILLIAMS. 

